Abstract: The invention pertains to a nuclear fuel rod for a nuclear reactor. The fuel rod has a cladding. The cladding's external surface has a surface texture that includes a rib. The rib coils around the circumference of the cladding. The rib length forms a sequence of continuous rib loops uniformly spaced along an axial length of the cladding. The ratio of rib height to cladding diameter is greater than or equal to 0.0134 and less than or equal to 0.0268. The ratio of rib height to rib width is greater than or equal to 0.8 and less than or equal to 1.2. A pitch measured between adjacent rib loops is greater than or equal to 9× rib height and less than or equal to 12× rib height. The rib enhances fuel rod heat transfer in a region downstream of grid mixing vanes, where turbulence is dissipated.

Abstract: A spacer grid design for a nuclear fuel assemblies that exhibits increased crush strength. The walls of the grid straps that surround the fuel elements have a number of dimples and/or springs with the flat surfaces of those walls formed with a plurality of emboss geometries that are formed in a symmetrical pattern with the pattern covering substantially an entire area of the wall except for the contact surfaces of the dimples and springs that interface with the fuel rods.

Abstract: The invention pertains to a nuclear fuel assembly in a nuclear water reactor. The fuel assembly includes an array of a plurality of axially extending elongated tubular nuclear fuel elements having first and second closed ends and encapsulating a fissionable material axially along at least a portion of an interior volume thereof and an exterior of at least one of the fuel elements. The fuel elements include a cladding that extends substantially axially between the first and second closed ends. The exterior surface of the cladding is modified to include a surface texture varying axially in a prescribed pattern along at least a portion of an axial length of the cladding. The surface texture includes a plurality of ribs placed parallel to one another and circumferentially around one or more of the fuel elements. Each of the plurality of ribs has a specified height, width, and pitch between each of the plurality of ribs.